Introduction
Sustainable transport, preserving the options for future generations, requires, among other things, achieving Net Zero carbon emissions and Vision Zero1 fatal and injurious crashes. We talk a lot about these ideas in the transport planning field, but we haven’t collectively confronted what is one of many steps required to achieve this, the near elimination of private cars in the urban sphere.2
We cannot be sustainable within the timeframe required (yesterday) with 2 billion cars on the planet, nor even 2 billion electric cars, nor even 2 billion automated electric cars. Our only hope is 2 billion automated electric cars produced by fairies who fart a CO2 absorbing compound.3
But we cannot eliminate cars in a democracy without people willing to do so.4
To illustrate the general concept, I will use Sydney as an example, but feel free to apply this argument to your own metropolitan area. I will note Sydney is an easier ask than all other Australian and North American cities, as it is already closer to the goal. As of the last pre-COVID Australian Census (2016), greater Sydney’s active plus public transport work trip mode share was just under 33%, comprising:
Public Transport (PT) ~27%
Bike ~1%
Walk ~5%.5
So the share of active + public transport6 for all commute trips would need to triple to be sustainable. Moreover, the total number of those trips would rise as the population grows, and fall if people switch to work from home.7 Current goals in the recently released Transport for New South Wales Active Transport Strategy call for doubling walk and bike trips in the next 20 years. This is insufficient to achieve sustainability from the surface transport sector.
However, achieving 100% sustainable travel in the metropolitan area would not simply triple the pre-existing modes and look like 81% PT, 3% Bike, 15% Walk. Expecting 81% transit use is expensive to supply because origins and destinations are too diffuse.
Instead, for Sydney it would look more like 60% Public Transport, 20% Bike and Micromobility, 20% Walk. So transit needs to about double its share, walk quadruple its share, and bike requires a 20-fold increase.
What would be required for Sydney to have (almost) 100% sustainable transport work trip mode share, voluntarily?
Voluntarily, here means no prohibitions on car use, no confiscation of automobiles, no extra car taxes beyond equivalence to other goods and to recover the fixed costs and externalities they impose on society, no extra tolls or road prices above and beyond what is required to pay for the full costs of automobility, etc.8 In short, for this to be politically acceptable, people need to be enticed out of their vehicles. Even if we raise the cost of auto travel so that people would pay the full cost of their automobility, pushing them to switch modes, they need something to switch to, and will be angry if the alternatives are perceived as significantly worse. So we need to think in terms of both Carrots and Sticks, not just Sticks. First the Carrots.
The Carrots: Improving the Alternatives
The place sustainable transport serves best (the Sydney CBD) PT already dominates, and can only increase share a little bit. Thus PT needs to find new, non-CBD oriented markets. Walk and Bike also over-perform in the CBD, so the proportionate increases in non-CBD areas need to increase even more than the previous paragraph suggests. We will take these modes in order:
Better Transit Service
Although there are plenty of extra seats on trains and buses, they are not going where and when people want to go.
We must change where transit goes, and change where people want to go.
Still, a doubling of transit share well within the grasp of Sustainable Sydney.
This includes a variety of steps:
Continuing the new metro and trains investment already committed and planned as described in the Future Transport Strategy. Build more of Bradfield’s 1916 Plan on Electric Railways for the City of Sydney, which are still good routes.
Improving the signals on existing train lines so that they can be more automated and have tighter headways (and thus more service).
Ensuring train stations have accessible entrances and exits on each end of the platform to maximise accessibility.
Deploying a FAST 2030 electric bus network or something like it. Including
Prepayment at bus stops and all-door boarding
High quality static and dynamic transit information
Bus signal priority at intersections (even when 100% sustainable transport share is achieved, there will be traffic signals to manage conflicts in crowded areas)
Bringing back more lighter rail on major arteries once served by trams.
Having a point-to-point (distance-based) fare structure that does not discriminate against modes.
Redesign the ferry network to better support trip interchanges (and convert to electric ferries)
High frequency all-day service is a positive feedback system: more service leads to higher frequencies leads to shorter waits leads to higher demand leads to more service. This will encourage more people to turn up and go with the confidence that they won’t have to wait too long if they just miss the train or bus.
More Walking
Moovit reports the average walk trip in Sydney is 0.66 km, and 19% walk more than 1 km for a trip every day. So a 20% mode share doesn’t seem out of reach. In the City of Sydney proper (which includes the CBD and some surrounding areas), walk comprises 17% of commute trips, and more of several other trip purposes. A strong majority wanted to walk more. Carrying things was the primary deterrent. The new logistics and rise of delivery is creating an opportunity mitigate this deterrent. Personal robots following us like loyal pets are not out of the question this decade.
Many short trips (under 2 km) that are now driven are walkable?9 Horace Dediu (@asymco - who everyone should follow) reports ~10% of US trips at 0-1 mile, ~11% at 1-2 miles, and ~12% at 2-3 miles. This implies about 15% of vehicle trips are under 2 km. Assuming Australian data are similar, replacing almost all of those with walking (or biking) is entirely feasible with no change in land use. Adding that to the 5% who already walk, and the 20% for walking is an easy-peasy goal for a Sustainable Sydney compared to the other modes.
A big component of short and unnecessary auto travel is parents (or grandparents) driving children to school. While everyone should have school choice, that school choice should involve independent travel by children. Similarly that bane of upper-middle class eastern Sydney parents, Saturday sports, could surely be organised better and played in transit accessible locations. If schools are too far to walk or ride to, maybe they should be made smaller and put in every neighbourhood. There are many vacant commercial, industrial, and religious facilities that could be repurposed for small neighbourhood schools (which are probably better than the larger mega-schools which have arisen in the past few decades). And a road network with far fewer private cars would be far safer to walk in.
Protected Bike Lanes
In contrast, a 20% Bicycle and Micromobility Mode Share might seem outrageous, a 20-fold increase. But it is less than the share in many cities globally found before the e-bike revolution. This list shows more than 60 cities with a higher than 20% bike mode share. Cities in the Netherlands, Denmark, Sweden, Japan, and China place highly. Australia has a high bike ownership per capita (>0.8) (higher than car (<0.6)), but much much lower bike use. Australians want to bike, but don’t. Why?
Many short trips are bikeable. BITRE summaries (fig 7a) of 2011 Census data (the most recent I could find easily) have about 25% of work trips under 5km, and another 22% 5-10 km, easily bikeable with the right network.
What do successful bicycle cities have in common? They provide infrastructure for biking. They are places where bicyclists rightly feel that they are not risking their lives in traffic. Vision Zero is a Net Zero issue. If people feel unsafe walking or biking, they will walk or bike less — and drive more.
The extent of the existing protected bike lane network of Greater Sydney is shameful.10 While the government’s proposal to add 1000 km of bike lanes is better than the alternative of not adding them, it falls far short in comparison to the size of the network serving motor vehicles, which includes:
160 km of motorway
2800 km of carriageway, 7000 lane km.
As a point of comparison on the Sydney Trains network (excluding Sydney Metro) 1821 km of track are maintained of which 1536 km is electrical.11 Given the different, more diffuse nature of bike trips than train trips, the network should be even longer than the highly concentrated trains network.
Even if local residential and shopping streets are slowed to a 30 km/h speed limit, a speed bicyclists will feel comfortable riding on, the arterial network will not be so slow, and travel among the buses, trucks, and remaining cars will be discouraging to many prospective bicyclists.
In any case, anyone from the all-powerful bike lobby will be able to provide good advice on all the things to do, which links to convert first, and so on. Note they support “1000 km of connected, safe, and direct cycle and micromobility routes per year”.
Road Space Reallocation
Road space must be reallocated as part of that enticement.
So a Sustainable Sydney would pedestrianise streets and prohibit nearly all private cars in the following locations:
surrounding schools,
in shopping precincts, and
throughout the region’s CBDs to enable pedestrians, buses, trams, bikes, trucks, emergency vehicles, and transport for people with special mobility needs to move unimpeded by private cars.
Elsewhere we would reallocate lanes from general traffic to buses, trucks, or bicycles (and thus take away lanes for cars: both moving and parked), but only when that reallocation was expected to increase person or freight throughput (so no more lanes than required).
So as a first cut for a rule for road space reallocation, every road with more than 2 lanes in one direction would need at least one of those lanes to be a transit lane, and would also need a bike lane. This is necessary to achieve a Sustainable Sydney.
Increasing X-from-Home
The pandemic demonstrated that work-from-home, shop-from-home, etc. was feasible for many people, and the continuation of this for office workers may be one of the lasting outcomes of the shock. That change significantly reduced commuting, especially commuting by public transport. However overall vehicle kilometres of travel has remained similar, as other travel substitutes for commuting while people try to retain their overall travel budget and continue to want to leave the house sometimes. This is related to induced demand. Less commuting lowers travel time which induces travel for other purposes that may have been priced off the road previously.
15-minute and 30-minute Networks and Places
Broadly, Sustainable Sydney requires achieving the 15-minute neighbourhood and 30-minute city concepts. In a 15-minute neighbourhood, everything you need for daily life, except your job, but including a public transport node, is within a 15-minute walk (one-way) of your home. In a 30-minute city, everything is within a 30-minute (one-way) transit ride or bike trip from your home. The transit objective is extremely difficult, as today’s one-way transit commutes average well in excess of 30 minutes. The only way this could be achieved is by moving new jobs to where people live and new housing to where the jobs are. In short:
Rebalancing Jobs and Housing
We cannot significantly (or quickly) change existing residential land use patterns. As a practical matter, we are not going to tear down many existing homes. Nevertheless, we have plenty of opportunities with new land use developments, which could be access-oriented designs.
Shorter trips are critical for achieving a 30-minute city, so that transit is a feasible competitor to the car, and so that walking and biking and reasonable choices for far more people than today. This can only be accomplished with a redistribution of activities.
The Stick: Raising the Price of Travel by Car
All of the above may not be sufficient if automobility remains subsidised. Ensuring cars and trucks pay their full cost for road use, including paying for the construction and maintenance of road infrastructure, road wear, and externalities such as CO2 emissions, air pollution from tail pipes, brakes, and tires, water pollution from run off, noise, and crash risk, among other costs will notably increase the price of travel, encouraging many drivers to switch modes even if nothing were done to improve the new mode. Making other modes better should be synergistic. There are (and should be) some debate about this, but we all know that in Australia, cars are not paying their full cost, and in the US, it is even worse.
Discussion
Transport is a large share (18%) of total emissions in Australia.12 The largest share of that is urban road traffic. A Sustainable Sydney strategy, or something like it, is necessary, though not sufficient, to achieve zero emissions overall. If we cannot eliminate cars where they are needed least (in high density urban areas with good public transport and a good climate for walking and biking), we probably do not have the political will to do the other, harder things required to achieve zero emissions either.13
I put Vision Zero in here as well as Net Zero because people who are killed by cars will of necessity reduce the size of future generations, car crashes are unsustainable for people at the individual level, though society may survive without any particular genetic line.
We also need to identify where the urban sphere begins and ends for these purposes. At a minimum, we can think of the urban sphere as anywhere built during the Tram era (served by trams through the 1950s), and anywhere within 15-minutes of a train or metro station.
IPCC Report concedes we will need to adapt and mitigate climate change. I’m an engineer, I like technology. Direct Air Capture is not impossible, but there is no evidence it will scale to the necessary size in sufficient time to offset enough carbon emissions to avoid many of the negative effects of climate change.
There is of course the “War on Cars”, a rhetorical attack on any limits on auto-mobility. And like many oppressed groups, a few car opponents have embraced the slur as a their brand.
This excludes work from home (which isn’t really a trip, but the absence of trip), and also doesn’t include non-work trips, which will bias even more towards private vehicle.
I am assuming useful public transport, electrified of course. By useful means that it serves more people-km per ton of metal moved than a car would. So largely empty buses (or trains) don’t help much. Some of that emptiness is necessary for repositioning to serve higher loads in another direction, much of that is just poor network design.
COVID increased work-from-home almost everywhere, as well as walk and bike mode shares, but public transport fell precipitously and has of this writing yet to recover, if ever, to pre-COVID levels. We will have to see how this plays out in coming years. If people retain transit reluctance, the future share of PT will fall and the share of active transport modes will rise.
Charging for the full costs of automobility will of course raise the cost of driving. That alone would be insufficient to eliminate driving, as the high taxes on fuel in European countries demonstrate.
Sadly, and for unconvincing reasons, the raw data from the Sydney Household Travel Survey is unavailable to anyone not working at the agency, and only useless summary statistics are downloadable.
This is the City of Sydney map. Look for the solid lines. Then try to figure out which of those lines are actually shared footpaths rather than protected bike lanes.
Sydney Trains Annual Report (2021)
National Transport Commission of Australia (2022) Light vehicle emissions intensity in Australia
Almost zero car travel probably would be pretty close to sufficient to achieve zero deaths from surface transport in the Sydney region, the occasional bike-bike or bike-ped or bus- bike or truck-bike or truck-ped or truck-bus, etc. collision notwithstanding.
Thanks David. You raise good points. However, I have a concern about the way you structure the analysis.
Like many travel demand studies it is based largely on commute mode share data, simply because that is the easiest data set to obtain. However, it is a poor indicator of travel activity, particularly active and micro modes (walking, bicycling, e-bikes and their variants). These statistics ignore non-commute trips, children’s travel, recreational travel, and active links of trips that include motor vehicle travel. For example, a bike-transit-walk trip is classified simply as a transit trip, and trips between parked vehicles and destinations are ignored even if they involve several blocks of walking.
The U.S. census reports that only 3.6% of commute trips are by active modes, which makes these modes seem insignificant, but the National Household Travel Survey, indicate that active modes serve a much more significant 12% of total trips, with higher rates in denser areas where traffic and parking problems are most severe, and various studies suggest that this share increases significant if communities invest a fair share of dollars and road space in serving those modes. In other words, there is significant latent demand for non-auto travel.
Improving active and public transport often leverages larger reductions in automobile travel, so each additional mile walked or biked reduces more than one vehicle-mile, for the following reasons:
• Shorter trips. Shorter active trips often substitutes for longer motorized trips, such as when people choose a local store rather than driving to more distant shops.
• Reduced chauffeuring. Better walking and bicycling conditions reduces the need to chauffeur non-drivers (special trips to transport a passenger). These often require empty backhauls (miles driven with no passenger). As a result, each mile of avoided chauffeuring often reduces two vehicle-miles.
• Increased public transit travel. Since most transit trips include walking and bicycling links, improving these modes supports public transit travel and transit-oriented development.
• Vehicle ownership reductions. Active mode improvements allow some households to reduce their vehicle ownership, which reduces vehicle trip generation, and therefore total vehicle-miles.
• Lower traffic speeds. Active travel improvements often involve traffic speed reductions. This makes non-auto travel more time-competitive with driving and reduces total automobile travel.
• More compact development. Walking and bicycling help create more compact, multimodal communities by reducing the amount of land needed for roads and parking, and creating more attractive streets.
• Social norms. As active travel increases, these modes become more socially acceptable.
This suggests that investments in non-auto modes can provide larger reductions in automobile travel than predicted by most modes that assume modest demand and one-to-one substitution effects.
For more information see:
Todd Litman (2022), "Fair Share Transportation Planning: Estimating Non-Auto Travel Demands and Optimal Infrastructure Investments," Victoria Transport Policy Institute (www.vtpi.org); at www.vtpi.org/fstp.pdf.
Todd Litman (2023), Comprehensive Transportation Emission Reduction Planning, Victoria Transport Policy Institute (www.vtpi.org); at www.vtpi.org/cterp.pdf.